Patients with respiratory ailments, in particular patients with COPD (Chronic Obstructive Pulmonary Disease), have impaired exercise tolerance and diminished ventilatory efficiency. For example, one symptom of both asthma and COPD is Dyspnoea. Dyspnoea, exercise limitation and reduced quality of life are common features of COPD. Dyspnoea induces a progressive downward spiral that starts with physical activity. Thus, the intensity of Dyspnoea is increased when changes in respiratory muscle length or tension are inappropriate for the outgoing motor command, or when the requirement for respiratory work becomes excessive.
There are a multitude of inputs to the sensation of Dyspnoea, few of which are readily modifiable. Dyspnoea may be alleviated by reducing the load placed upon the inspiratory muscles. Patients with COPD frequently have inspiratory muscle dysfunction, exhibiting weakness and reduced endurance. Patients with COPD may be well adapted to generating low flow rates for long periods of time, but this adaptation may rob them of the ability to generate the high pressures and flow rates required during exercise. The demand for exercise ventilation in patients with COPD may be elevated by their deconditioned state, inefficient breathing patterns, and gas exchange impairment.
Various techniques have been developed to improve respiratory muscle endurance capacity. For example, one technique involves respiratory muscle training through the use of positive expiratory pressure devices, such as the AEROPEP PLUS valved holding chamber available from Trudell Medical International, the Assignee of the present application.
Another technique is referred to as Respiratory Muscle Endurance Training (RMET). Most current RMET techniques require complicated and expensive equipment, which limits widespread use. Alternatively, a portable tube has been developed for use by COPD patients, and has been effective in improving the endurance exercise capacity of the users.